Vacuum cleaner, the driving motor of which is arranged for running at two different velocities



Dec. 18, 1962 1 o. J. G. HANSEN .3

VACUUM CLEANER, THE DRIVING MOTOR OF WHICH IS ARRA G FOR RUNNING AT TWODIFFERENT VELOCITIES Filed. July a, 1958 INVENTOR Ove Johannes Git/5Hansen BY QM, 9w, M244 v wzMA/ ATTORNEYK United States Patent Of"3,069,068 VACUUM CLEANER, THE DRIVING MOTOR OF WHICH IS ARRANGED FORRUNNING AT TWO DIFFERENT VELOCITEES Ove Johannes Grejsen Hansen, Lyngby,Denmark, assignor to Aktieselskabet Fisker & Nielsen, Copenhagen-Frederiksherg, Denmark Filed July 8, 1958, Ser. No. 747,152 Claimspriority, application Denmark July 15, 1957 4 Claims. (Cl. 23012) Avacuum cleaner is known, the driving motor of which is arranged forrunning at two different speeds, and in which the switchover from onespeed to another of the motor is eifected by means of a feeler arrangedfor being actuated by a pressure difference, produced by the fan of thevacuum cleaner, between two different zones inside or outside the vacuumcleaner. This known vacuum cleaner is so arranged that when the vacuumin the suction nozzle of the vacuum cleaner is slight or nil, the feeleris in the position where the motor is set to the highest of the twospeeds while at increasing vacuum the feeler will move into its otherposition where the switch will then switch over to the low motor speed.

This known vacuum cleaner is particularly intended for the vacuumcleaning of carpets in the special way that the carpet is lifted by thesuction nozzle, the edge of the latter being in contact with the carpetand forming a scaling for air. Dependent on the weight and closeness ofweaving of the carpet the motor of the vacuum cleaner adjusts itself toa speed and a suction effect deriving therefrom which are adapted to thecarpet that is being cleaned. This known vacuum cleaner will, however,be unsuited for the vacuum cleaning of light and open fabrics, such ascurtains, as due to the ample amount of air passing through such fabricsthere will only be a slight vacuum in the suction nozzle, for whichreason the switch willswitch over to the high motor speed so that stillmore air will be sucked through the open and not very resistant fabricwhich may be torn thereby. The known vacuum cleaner has the furtherdrawback that the motor starts at its highest speed, and hereby the sizeof the motor and thereby the maximum capacity of the vacuum cleaner arelimited out of regard to the permissible current pulse at the start ofthe motor.

The invention aims at remedying thesaid drawbacks and providing animproved vacuum cleaner with a high maximum suction capacity and inwhich the suction capacity and the quantity of air sucked through thevacuumcleaned objects can be regulated easily and reliably. There will,for example, in the case of the vacuum cleaning of carpets and furniturebe aimed at attaining the highest possible pressure difference betweenthe pressure and vacuum sides of the fan unit simultaneous with thegreatest attainable quantity of air sucked through the object, while inthe vacuum cleaning of small light rugs and similar objects it will bedesirable to be able to reduce the suction capacity of the vacuumcleaner in order to prevent the objects to be vacuum-cleaned from beingsucked on to the nozzle and carried along with the latter.

in the case of vacuum cleaning of particularly light objects, forexample thin curtains, it will also be convenient to be able to reducethe quantity of air sucked through them as explained above.

In known, universally applicable vacuum cleaners these facts havenecessitated a solution by compromise which limits the maximum suctioncapacity of the vacuum cleaner while at the same time the user of thevacuum cleaner must take particular care when vacuum cleaning lightcurtains etc.

With a view to gaining the aims stated, the invention relates to anarrangement in vacuum cleaners of the type 3,069,053 Patented Dec. 18,1962 referred to by way of introduction, and the characteristic featureof the invention is that the feeler is arranged for switching the motorto the low speed when the said pressure difference is very slight ornil, and for switching to the high speed at the pressure differenceoccurring when the vacuum cleaner operates with full opening.

Hereby it is attained that at the start of the motor of the vacuumcleaner, when the fan is stopped and hence the pressure difiference isnil, the motor will be set to the low speed so that its starting currentwill be reduced, while at the same time the mechanical stresses on themotor and the fan are reduced, and this has a favourable influence onthe lifetime of the whole unit. Due to the reduced starting current thevacuum cleaner may be provided with a larger motor and thereby a morepowerful fan than would be the case if themotor were to start at itsmaximum speed. During the vacuum cleaning, the motor will automaticallybe switched over to the high speed, which gives the maximum suctioncapacity, due to the pressure drop caused by the passage of the airsucked in through the objects that are being vacuum cleaned. When themotor and thereby the fan are stopped at the ordinary main circuitbreaker, the feeler will at once switch the motor to the low speed usedat the start.

A known vacuum cleaner having a dust separation filter is provided witha feeler which reacts on the pressure drop across the filter. At acertain degree of obstruction of the filter resulting in a rise in thepressure drop this feeler causes the switching in of a mechanicalcleaning mechanism for removing the dust from the filter, and at thesame time the rotational speed of the vacuum cleaner motor is increased.In this known vacuum cleaner the switching of the motor speed is,however, effected as a link in a special operation during which thenormal functioning of the vacuum cleaner is interrupted. There is onlyone motor speed at disposal for the vacuum cleaning, and the capacity ofthe vacuum cleaner is, as was the case with the vacuum cleaner firstreferred to, limited by the motor always starting at its normaloperation speed. Therefore, also in the case of this vacuum cleanerthere is no possibility of regulating the suction capacity with dueregard to the work to be performed.

In an expedient embodiment of the invention a threeway cock is provided,by means of which one side of the feeler can alternately be brought intoconnection with two different zones inside or outside the vacuumcleaner, one of which may be the zone which is in connection with theother side of the feeler. With such a three-way cock it is possiblemanually to put the feeler out of action, so that the motor constantlyruns at one of the two possible speeds, in particular the low s eed,desirable in the vacuum cleaning of light objects requiring reducedsuction capacity and air passage. The feeler is advantageously accordingto the invention a diaphragm clamped along its periphery, and its motionis transmitted through a one-armed lever to the switch which ispreferably designed as a quick-break switch. The diaphragm can be madeexceedingly sensitive to small differences in pressure, and the use of aone-armed lever between the diaphragm and the switch permits aconversion of a comparatively large travel of the diaphragm at a smallforce into a small travel and a comparatively large force at the switch,so that the position into which it is switched is a very well-defined.

According to the invention the feeler and the switch are convenientlymounted inside part of the vacuum cleaner, so that one side of thefeeler is in direct contact with the air in this part of the vacuumcleaner, while the other side of the feeler is by a tubing connectedwith another zone inside or outside the vacuum cleaner. By thismounting, all problems in connection with a sealing G9 around themovable parts, which transmit the motion of the feeler to the switch,are avoided.

in an embodiment of the invention the driving motor of the vacuumcleaner is a universal motor with taps on the field coil for obtainingthe two difierent speeds. This gives a no-loss regulation of the speed,and the motor can be used for alternating current as well as for directcurrent.

The invention will in the following be described with reference to theaccompanying purely diagrammatic-a1 drawings which show an embodiment ofthe invention and where:

FiG. 1 is a part section through a vacuum cleaner according to theinvention,

FIG. 2 is an illustration on a larger scale of a combined teeler andswitch for a vacuum cleaner according to the invention,

FIG. 3 is a section on line IIiIlI in PEG. 2,

FIG. 4 is a perspective illustration of a detail of the vacuum cleaneraccording to the invention, and

FIG. 5 is a schematic diagram of the electric motor circuit.

The dust container of the vacuum cleaner is designated by 1. It is by afilter 2. separated from the suction chamber 3. An electric motor 5 isby clamping means, not shown, secured to a motor carrier 4 securedinternally in the suction chamber. The shaft 6 of the motor carries anumber of vanes 7 which together with stationary guide vanes 8 form thefan unit of the vacuum cleaner. During its operation, the fan sucks airfrom the suction chamber 3 and blows it into the pressure chamber 9which is provided with an exhaust branch, not shown, to thesurroundings.

Internally in the pressure chamber a combined feeler and switch 19 issecured, which is shown in detail in FIGS. 2 and 3. On a common base 11,which is made of an electrically non-conducting material, a switch issecured consisting of a central, resilient contact member 12 and twostationary contact members 13 and 14, of which the member 13 is locatedbelow the central contact ember 12, while the contact member 14 islocated above the latter. The central contact member 12 is T-shaped witha long stern 12a and two shorter branches 12b and 12c parallel to thestem. The said three parts are held together by a transverse member 12a.

The contact member 12 is made of an electrically conductive and at thesame time resilient material, as e.g. copper. It is secured to the base11 at the end of the long stem 12a with at least one screw 15 which atthe same time can serve as supply terminal for the current supply. Thetwo side branches 12b and 12c are curved and supported by the base 11 insuch a way that they can perform a limited angular turning in the pointof support, and the side branches and their supports are furthermore sodesigned that, when the contact member 12 is not subjected to an outerstress, they keep it with a suitable resilience against the stationarycontact member 14, so that there is contact between a contact point5.6:: on the contact member 12 and a contact point lab on the contactmember 14.

The contact member 13 carries a corresponding contact point 17b, asshown in FIG. 5, which can get into electric contact with a contactpoint 17a on the contact member 12, when the switch is in its otherextreme position.

On the underside of the base 11 an elastic diaphragm 13 is mounted whichis clamped along its periphery by means of a box 19 secured under thebase, which box together with the diaphragm forms a chamber that issealed air-tight from the pressure chamber. The box 19 is provided witha branch 26 on which a flexible tube 21 is slid so as to fit air-tightaround the branch. The box 13 may expediently be pressed from sheetmetal, and the branch 2% may be brazed to the box or may be madeintegral with the latter. The flexible tube may e.g. be made of extrudedplastic.

To the on wards-facing side of the diaphragm 18 a pin 22 is secured,e.g. as shown by the bending over around a collar on the pin 22 of anumber of tongues on a reinforcing disc 23 glued on to the middle of thediaphragm. In the vicinity of its outer end the pin 22 is provided withan annular construction, with which a one-armed lever 24 engages whichis shown perspectively and on a larger scale in FIG. 4.

The lever 24 has the form of an inequilateral angle, the long side 24aof which runs substantially parallel to the diaphragm 18 and the contactmember 12a. In its front end the side 24a is provided with a U-shapednotch 2412 which fits across the annular constriction on the pin 22, sothat the lever can be slid radially across the pin, but in the axialdirection of the latter is substantially secured by the constriction.

The short angle side 240 of the lever 24 has a closed slit 24d which canbe slid over the contact member 12a. Close to the side 24c two bent-overtongues 24s are pro- -vided, which, one from either of the edges of theside 24a, extend over the contact member 12a.

The tube 21 is led to a three-way cock 25 which is secured to the wallof the pressure chamber 9 of the vacuum cleaner. Its shank is carriedair-tight out through the wall and on the outside carries an operationknob 26. From the cock 25 a tube 27 passes air-tight through the motorcarrier 4 down into the suction chamber 3, and the cock is furthermoreprovided with a transverse bore 28 which opens into the pressurechamber.

The driving motor 5 is a series-wound universal motor. Its field coil30a, 301), see FIG. 5, has a tapping 31, whereby the motor can rotate attwo different speeds dependent on the current supply being connected toeither the terminal of the coil portion 3% or the tapping 31. Thetapping 31 of the field coil portion 30b corresponding to the highermotor speed is connected to contact point 17b ou contact member 13 ofthe switch, and the terminal of the coil portion 30b is connected tocontact point 161'; on contact member 14. A current supply source may beconnected to terminals 33 and 34 which are connected to the terminal ofthe coil portion 38a and the terminal screw 15 on contact member 12,respectively, a main circuit breaker 32 being inserted at a suitablepoint of the electrical circuit.

During normal operation of the vacuum cleaner the three-way cock 25 isset so as to permit passage from the tube 21 to the tube 27, which meansthat the chamber under the diaphragm 18 is in communication with thesuction chamber 3. When the motor is stopped, there is no difference inpressures between the suction chamber and the pressure chamber, and thediaphragm is in its position of rest, in which the contact member 12 isheld against the contact member 14 by the springs 12b and 12c.

When the current is closed by operating the main circuit breaker, themotor will start at its lowest speed. Hereby a certain vacuum isproduced in the suction chamber 3, so that the diaphragm 18 is suckedinwards in the box 19. The pin 22 exerts a pull in the lever 24, and thelatter will bear with its tongues 242 against the upper side of thecontact member 12a, while the short angle side 24c moves upwards, untilthe underside of the closed slit 24d bears on the underside of thecontact member 1211. v

The lever 24 thus actuates the contact member 12 against the springs 12band 120, and at a certain value of the pull in the diaphragm the contactmember will momentarily snap over so as to get into electric connectionwith the stationary contact member 13, and hereby the speed of the motoris switched over to its highest value, as shown in FIG. 5.

The switching described occurs at a vacuum which the fan produces atfull opening. Thereby the motor will, when the knob 26 is in the saidposition, run at its highest speed, and the vacuum cleaner operates atits highest capacity. When the current is interrupted at the maincircuit breaker, and the motor stops, the pressure difference on the twosides of the diaphragm 18 is eliminated, so that the contact member 12ais by the springs 12b and 12c returned to the position shown in FIG. 3,and a restart of the motor will therefore always occur at the lowestspeed, so that the start current pulse is limited.

When the operation knob 26 of the three-way cock is turned 90, the tube21 is put into communication with the transverse bore 28 of the cock,while the tube 27 from the suction chamber is blocked. Both sides of thediaphragm 18 are now in communication with the pressure chamber 9, sothat no pressure difference can occur here, and when the motor isstarted, the contact member 12a will therefore remain in contact withthe contact member 14, so that the motor will continue running at thelow motor speed and with reduced suction capacity. It will be seen thatit is possible during the operation of the vacuum cleaner to alternateoptionally between the two motor speeds by operating the knob 26.

The invention is not limited to the embodiment shown, but may be variedin different ways within the scope of the invention. The switch may forexample be mounted in the suction chamber or possibly on the outside ofthe vacuum cleaner, and one side of the diaphragm may be incommunication with the surroundings. The switch may also be designed inother ways than that here described, the sole condition being that ithas a welldefined switching point between the two positions.

I claim:

1. A vacuum cleaner comprising a housing having an air inlet and an airoutlet, a fan disposed within said housing, a two-speed electric motordrivingly connected to said fan, electric switch means connected to saidmotor for causing said electric motor to rotate at either of its twospeeds, pressure responsive means in communication with the air inletand air outlet and being responsive to the pressure rise across saidfan, means mechanically connecting said pressure responsive means tooperate said switch means so as to set the motor to rotate at the lowerspeed thereof when said pressure rise is substantially zero, and to setthe motor to the higher speed thereof when said pressure rise assumes avalue corresponding to the normal operational conditions of the fan,said switch means being normally in its low speed setting, and manualmeans selectively operable to render said pressure responsive meansinoperative so as to maintain said switch means in the position of thelower motor speed.

2. A vacuum cleaner as claimed in claim 1, in which said last-mentionedmeans comprises a manually operable three-way cock arranged to provide acommunication across the pressure responsive means and to disconnect itfrom the air inlet.

3. A vacuum cleaner comprising a housing having a suction chamber and apressure chamber, an air inlet to said suction chamber and an air outletfrom said pressure chamber, a fan disposed within said housing betweensaid suction chamber and said pressure chamber, a two-speed electricmotor mounted in said housing and drivingly connected to said fan, saidmotor having a first winding for a lower motor speed and a secondwinding for a higher motor speed, means defining an air-tight boxlocated within one of said two chambers and including a diaphragm, meansfor establishing a communication alternately from the interior of saidbox to either of said two chambers, a pivotally mounted leveroperatively connected to said diaphragm, first and second movablecontact means secured to either side of said lever, first fixed contactmeans arranged to engage said first movable contact means when thepressures on either side of said diaphragm are substantially equal,second fixed contact means arranged to engage said second movablecontact means at a pressure difference between the two sides of thediaphragm corresponding to normal operation of the vacuum cleaner atfull opening, electric connections from said first set of contact meansto a current supply and to said first winding of said electric motor,respectively, and electric connec tions from said second set of contactmeans to a current supply and to said second winding of said electricmotor, respectively.

4. A vacuum cleaner comprising a housing having a suction chamber and apressure chamber, an air inlet to said suction chamber and an air outletfrom said pressure chamber, a fan located within said housing betweensaid suction chamber and said pressure chamber, a two-speed electricmotor drivingly connected to said fan, said motor having a first windingfor a lower motor speed and a second winding for a higher motor speed,means defining an air-tight box located within one of said two chambersand including a diaphragm, a manually operable threeway cock,communication means from the interior of said air-tight box to the inletopening of said three-way cock, communication means from the firstoutlet opening of said three-way cock to the other of said two chambersand communication means from the second outlet opening of said three-waycock to the first of said two chambers, a pivotally mounted leveroperatively connected to said diaphragm, first and second movablecontact means secured to either side of said lever, first fixed contactmeans arranged to engage said first movable contact means when thepressures on either side of said diaphragm are substantially equal,second fixed contact means arranged to engage said second movablecontact means at a pressure difference between the two sides of thediaphragm corresponding to normal operation of the vacuum cleaner atfull opening, electric connections from said first set of contact meansto a current supply and to said first winding of said electric motor,respectively, and electric connections from said second set of contactmeans to a current supply and to said second winding of said electricmotor, respectively.

References Cited in the file of this patent UNITED STATES PATENTS1,904,973 Smellie Apr. 18, 1933 2,046,675 Daiger July 7, 1936 2,140,143Sellers Dec. 13, 1938 2,439,239 Crever Apr. 6, 1948 2,570,222 Ell Oct.9, 1951 2,588,301 Snyder Mar. 4, 1952 2,758,670 Doughman Aug. 14, 19562,789,660 Brown Apr. 23, 1957.

